<!doctype html>
<html class="no-js">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="description" content="">
    <meta name="keywords" content="">
    <meta name="viewport" content="width=device-width, initial-scale=1,maximum-scale=1, minimum-scale=1">
    <title></title>
    <script>
        var deviceWidth = document.documentElement.clientWidth;
        if(deviceWidth > 640) deviceWidth = 640;
        document.documentElement.style.fontSize = deviceWidth / 6.4 + 'px';
    </script>
    <style type="text/css">
        body{
            margin: 0;
            padding: 0;
            width: 6.4rem;
        }

        .demo {
            width: 4.71rem;
            height: 4.71rem;
            margin: 2rem auto;
            background: url(chart.png) no-repeat;
            background-size: 100% 100%;
        }
    </style>
</head>
<body>
    <div class="demo">

    </div>
</body>
</html>